What is Green Optimized Charging?
Green Optimized Charging is a charging strategy that prioritises battery charging at moments when renewable or low-emission energy is available — for example, during periods of high solar generation or low grid carbon intensity. Instead of charging the battery opportunistically at any point, GOC directs charging toward these preferred windows, reducing the overall carbon footprint of your stored energy.
This is particularly useful for sites that want to align battery operation with sustainability targets, not just cost or peak shaving goals.
How to enable GOC in a simulation scenario
Open your Digital Twin.
Select your Battery and press edit
Locate the Green Optimized Charging toggle and switch it on.
The SOC level the battery will aim to reach during green charging windows is default 60%.
Save your scenario settings and run the simulation as normal.
Note: GOC is a simulation-side configuration. It can also apply to a Live EMS and the GOC percentage can be adjusted by Tibo.
How GOC affects BESS behaviour
When GOC is active, the battery's charging behaviour changes in a specific way:
During a window of cheap/free/green energy the battery charges up to the configured GOC SOC target — for example, 60%.
This pattern repeats across the simulation period: the battery charges to the target, is drawn down through normal operation (peak shaving, self-consumption), and then charges back up to the target during the next available green window.
The battery will charge up to 60% immediately when it has the chance and when it has energy available that is cheap or free.
The battery preserves headroom above the GOC target, which allows it to absorb additional renewable generation if it becomes available.
The battery will, however, not wait for even lower prices on EPEX or imbalance markets that may happen at a later moment during the day.
The battery will also charge with non-green energy if it needs it to prevent contracted capacity problems.
The battery will charge up to 60% even if it doesn't need the energy the following days.
Recognising GOC behaviour in simulation reports
After running a simulation with GOC enabled, you can verify the behaviour in the results charts:
Open the simulation report and go to the chart which shows the BESS State of Charge over time.
Zoom into a representative time window — a few days works well for most sites.
Look for a repeated pattern where charging cycles may stop/flatline at the GOC SOC target of 60%
If the pattern is clear, GOC is working as expected for that scenario.
Note: On very active sites where the battery is used heavily every day for peak shaving or self-consumption, the GOC pattern may be less visually obvious in the chart. Frequent draw-downs can make it harder to distinguish GOC-driven charging from regular cycling. In these cases, zooming into a quieter period — such as a weekend — can make the pattern easier to spot.
GOC combined with a highly active BESS
When GOC is enabled on a site where the battery is also working hard for other purposes (peak shaving, self-consumption, or both), the effect of GOC on the SOC chart may appear less prominent. This is expected behaviour, not a misconfiguration.
If the battery is being drawn down frequently, it will naturally need to recharge more often to meet site demand.
The GOC logic still operates, but its influence on charging behaviour is partially offset by the volume of discharge activity.
To see the GOC effect more clearly in these cases, compare a simulation run with GOC enabled against one without it, using the same scenario settings.
Best for: Sites with moderate battery usage and good renewable generation will show the clearest GOC behaviour in simulation results. High-utilisation sites will still benefit from GOC, but the charging pattern will be less distinct in the charts.